gms | German Medical Science

Objective: This study aims to investigate the responsiveness of the intact retina to electrical stimulation using novel soft electrodes (SoftC Probe). The objective is to address the limitations of ex-vivo studies, where distorted metabolic environments and stimulation protocols may affect outcomes.

Materials and methods: SoftC Probe electrode arrays, with 32 electrodes (50 µm diameter), were screen-printed using carbon ink on thin polyurethane films. The probes were tested on embryonic chick retinas in situ, enabling simultaneous electrical stimulation and electrophysiological recordings. An offline analysis pipeline was developed to remove stimulation artifacts, allowing automated identification of both direct responses and spontaneous activity.

Results: Effective electrical stimulation and simultaneous retinal activity recordings were achieved with the flexible probe, which conformed closely to the retinal surface. The offline analysis algorithm successfully removed stimulation artifacts, enabling accurate detection of direct responses to electrical stimulation and spontaneous activity. Stable and repeatable retinal responses were observed during prolonged stimulation, demonstrating the first indication of discrepancies between ex vivo and intact retina preparation.

Discussion: The SoftC Probe offers a significant advancement in neural interfacing technology, enabling the investigation of retinal function while preserving the retina's natural environment. This technology overcomes the limitations of ex-vivo studies and opens new avenues for research in vision restoration, with potential applications in retinal prosthetics and other neural interface technologies.

Acknowledgment: This work was supported by ERC grant “OuterRetina” and an ISF grant (538/22).